Expression and activity analyses of CTLA4 in peripheral blood lymphocytes in systemic lupus erythematosus patients

Abstract

The objective of this study was to determine the expression and activity of CTLA4 in T-cells of systemic lupus erythematosus (SLE) patients. Expression of CTLA4 on freshly isolated peripheral blood T-cells was evaluated in 33 SLE patients and 25 controls using flow cytometry. The T-cells from 19 SLE patients and 22 controls were stimulated and cultured with Chinese hamster ovary cells expressing CD80 (CHO-CD80) or with CHO cells. T-cell proliferation was determined with [3H] thymidine incorporation (CPM), and the inhibitory effect of CTLA4 on T-cell proliferation was evaluated by the ratio of CPM for T-cells with CHO-CD80 cells to that of T-cells with CHO cells (the CHO-CD80/CHO ratio). Intracellular CTLA4 expression in freshly isolated peripheral blood T-cells was significantly higher in SLE patients than the controls (P < 0.05), but there was no correlation with clinical features or disease activity. The CHO-CD80/CHO ratio of SLE patients was significantly higher than that of the controls (P < 0.05). Among SLE patients, the CHO-CD80/CHO ratio of patients with lupus nephritis was significantly higher than that of patients without lupus nephritis (P < 0.05). In conclusion, our data suggest that CTLA4 expression is not impaired in SLE patients, but there is a possibility of decreased inhibitory effect of CTLA4 involved in the pathogenesis of SLE.